The different qualities of mercy that Portia is talking about are forgiveness, kindness and compassion.No, it does not have any effect on Shylock.
Explanation:
The opening lines beginning with "the quality mercy is not strained " means that mercy should be freely given.
Mercy means an act of kindness and forgiveness to even the most unforgiving person. And by providing this act of kindness, not only the person on whom you bestow mercy is blessed , but in return the one who provides the mercy too finds peace in his heart.
She says that Mercy is abundant like rain, unlike something that,when strained becomes scarce .Mercy is abundant like the rain and can be freely given out.
It doesn't have any affect on Shylock as wants to have his pound of flesh from Antonio.
